1. Field of the Invention
The present invention relates to a package capable of mounting a crystal oscillator on a front surface of a package body and also mounting an electronic component inside a cavity formed in the package body.
2. Description of Related Art
For example, in order to be able to perform surface mounting of a crystal piece and mount an IC chip, a crystal oscillator for surface mounting, in which ceramic plates of three layers are stacked to form a container body and a peripheral portion on a front surface of the relatively thin-walled ceramic plate of the uppermost layer, is brazed with a seal ring (metal frame). Furthermore, an end portion of the crystal piece is bonded and supported to a front surface of the relatively thick-walled ceramic plate of the middle layer, an opening portion is formed in the front surface of the ceramic plate of the middle layer excluding the bonded portion of the crystal piece, and the IC chip can be mounted inside a cavity using a front surface of the ceramic plate of the lowermost layer as a bottom surface, has been proposed. See, for example, Patent Document 1.
However, the crystal oscillator had a problem that the thickness of the whole container body tends to become thick since the ceramic plates of three layers are stacked to form the container body.
Further, for example, in the case in which the seal ring joined to the ceramic plate of the uppermost layer is misaligned or a lamination misalignment between the mutual ceramic plates of the uppermost layer and the middle layer occurs, there was also a problem of becoming difficult to obtain space for the bonded portion for bonding the end portion of the crystal piece to the front surface of the ceramic plate of the middle layer.
Consequently, it was difficult to respond to needs for miniaturization of the whole including thinning of the container body in the crystal oscillator.